A conventional high-frequency integrated circuit device having a multilayer wiring plate is disclosed in Japanese Patent Application Laid-Open No. Sho 63-292660 and is illustrated in FIG. 4. As shown in the figure, the device primarily contains a laminated body 25 which is formed by sequentially laminating layers of an insulating plate 24 and thin metal layers 26. Specifically, a first insulating plate 24 is formed as the bottom layer, and a first thin metal layer 26 is formed on the first insulating plate 24. Then, a second insulating plate 24 and a second thin metal layer 26 are sequentially formed on the first thin metal layer 26, and a third insulating plate 24 is formed on the second thin metal layer 26. Cavities are formed in the third insulating plate 24 to expose portions 27 of the second thin metal layer 26, and electronic components 28 are adhered to the exposed portions 27. Similarly, cavities are formed in the first insulating plate 24 to expose portions 27 of the first thin metal layer 26, and electronic components 28 are adhered to the exposed portions 27.
The heat generated by the electronic components 28 is transmitted directly to the thin metal layers 26 and travels within the metal layers 26 only in a transverse direction (i.e. the horizontal direction in FIG. 4). However, if a PoGaAsFET or similar power device is adhered to the exposed portions 27 of the thin metal layers 26, the metal layers 26 could not sufficiently radiate the heat away from the power device. Therefore, the size of the metal layers 26 would need to be enlarged. As a result, the device in FIG. 4 cannot be used to create a micro power amplifier/module which houses a power device and which has a size of approximately 0.2 cm.sup.3.
FIG. 5 is a sectional view of a multilayer printed wiring plate disclosed in Japanese Patent Application Laid-Open No. Hei 7-50489. As shown in the figure, the wiring plate comprises a laminated body 29 having insulating plate layers. The laminated body 29 also contains pads 30 on its surface, and through holes 31 are formed though the pads 30. Also, a chip carrier integrated circuit ("IC") 32 is mounted on the pads 30 over the through holes 31, and the heat generated by the chip carrier IC 32 is radiated via the pads 30 and the through holes 31 to the atmosphere. Also, some of the heat which radiates via the through holes is transmitted from the holes 31 in a transverse direction (i.e. the horizontal direction in FIG. 5) to thin earth or grounding layers 33 which are laminated between the insulating layers in the laminated body 29. Then, the heat is radiated from the earth layers 33 to the atmosphere.
In the conventional device above, only the thin earth layers 33 and the radiating through holes 31 radiate heat away from the chip carrier IC 32. Therefore, in order to adequately radiate heat away from a PoGaAsFET or another power device element, the thin earth layers 33 need to be enlarged or increased in number. However, if the size or number of the layers 33 is increased, the device cannot be used to form a micro power amplifier/module of having a volume of about 0.2 cm.sup.3.
Another conventional micro power amplifier/module is shown in FIG. 6. As shown in the figure, the module comprises a ceramic substrate 35 which is provided with a wiring layer 8a, and a thick external radiating plate 36 is adhered to a rear surface of the substrate 35. Also, cavities are formed in the ceramic substrate 35 to expose a portion 37 of the radiating plate 36, and a power device element 2 is mounted on the exposed portion 37.
Although heat can be adequately radiated away from the power device element 2 via the plate 36, the module must be assembled by incorporating the thick external radiating plate 36 into the module. Therefore, the process by which the module is manufactured is complicated and expensive. As a result, the conventional device cannot be used to produce an inexpensive micro power amplifier/module which has a volume of approximately 0.2 cm.sup.3.
As described above, the conventional devices shown in FIGS. 4 and 5 cannot sufficiently radiate heat away from a power device element without enlarging the size of the metal layers contained in the laminated body. As a result, the size of such devices must be dramatically increased, and a micro power amplifier/module which has a volume of about 0.2 cm.sup.3 and which houses a PoGaAsFET or similar power device element cannot be produced.
Also in the conventional device shown in FIG. 6, the thick radiating plate is not laminated in a laminated body, but externally incorporated into the device. Thus, the manufacturing process of the conventional device is complicated and expensive.